Box closing machine



Sept. 2, 1958 D. G. KINGSLEY Box CLOSING MACHINE IN1/Emma 4 Sheets-Sheet 1 David G. Kings/ey- I wlmvmrw ATTORNEYS.

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Box cLosING MACHINE 4 Sheets-Sheet 5 Filed Jan. 27, 1954 S Y R# E m/ N .S .H ma. 0 V.m #U mK. A @im .,m V ,l a am Y B Sept. 2, 1958 .D. G. KlNGsLEY Box CLOSING MACHINE:

Filed Jan. 2'?, 1954 4 Sheets-Sheet 4 I INVENToR. David G. Kings/ey @YZ n .da Y

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J" Bief! 5 United tates Patent O BOX CLOSING MACHINE David G. Kingsley, Mountain Lakes,

Stapling'Machines C0. R of Delaware ockaway N. J., assigner to N. J., a corporation This invention relates to a machine for closing wirebound boxes (including crates) of the general type shown for example, in United States Patent No. 1,933,030. Sucli boxes are provided with encircling binding wires which have formed at their opposite ends loops ywhich come lnto opposition with each other at the closing corner of the box and one of such loops, beingA somewhat narrower than the other, may be inserted through the latter and bent down to secure the box closed.

Heretofore such boxes have beenclosed entirely by hand operations. In packing plants where large numbers of boxes are packed daily, the labor of closing the boxes 1s a substantial item of expense. By supplementing and partially lsupplanting this hand labor, the closing machine provided by the present invention enables an appreciable reduction 1n production costs. Moreover, by accomplishing'uniflormly good box closures, the machine reduces the possibihtyof accidental opening of the boxes in transit.

Thls machine, in general, includes a conveyor for moving the lled boxes into and out of the closing machine, guide rails for aligning and .laterally positioning the box and, if desired, for pressing the hingedly connected top of the box into snugly closing position, movable clamp members for gripping the box and stopping its movement when it reaches the proper position to be operated upon, and movable closing members for engaglng and bending the loops. The clamp vmembers andthe closing members are actuated by pneumatic cylinders, or other suitableV means, controlled either directly or indirectly by sensi-ng meansresponsive to the position of the box.

In the drawings:

Figure 1 is a front elevation of a box closing machine embodying features of the present invention.

Flgure 2 is a fragmentary sectional View of the machine taken on the 'line 2-2 of Figure l, showing the conveyor bands and their supporting rollers.

.Figure 3is a` side elevation of the closing machine as viewed from side appearing at the left in Figure 1',v` showing a wirebound box arriving in proper position to be operated upon.

Figure 4 is a fragmentary sectional View taken on the line 4 4 of Figure 3, showing the means for properly positioning and clamping the box for a closing operation.

Figure 5 is a fragmentary elevationalview of the rear upper portion of the closing machine with some parts shown broken away to reveal more clearly the means for raising or lowering the loop fastener-bending mechanism to accommodate boxes of dilerent height.

Figure 6 is a fragmentary sectional .view takenon the line 6-6 of Figure 5, showing one of these adjusting mechanisms.

Figures 7, 8, 9 and l0 are fragmentary elevational views of the upper portion of the closing machine,- lwith certain parts omitted, to show progressively the movement of the loop fastener-bending mechanism when performing a box closure. A

IFigure 11 is a fragmentary isometric View of a portion ICC of abox closing corner showing in broken lines the position-.of apair of interengaged loop fasteners and in full lines. theirposition after closure.

Figure:12is.a fragmentary end elevational view of the upper portion 'of the closingv machine,^with some parts removed,2showing an alternative arrangement of elements which are designed-to press the top or cover of the box down into closing position as well as bend the loop fasteners tozsecure the box closed.

Figure 1.3 is a side elevational view of the portion of the machine shown in Figure l2 as viewed from the side appearing at the right in Figure 12.

Figure 14 is a schematic diagram of the electrical circuit for controlling the air operated elements.

Referring. lirst to Figures l, 2 and 3, the bo-x closing machine includes a power-driven conveyor having a pair of endless flexible conveyor bands 2. As may be seen in Figure 3, the conveyor bands 2 are spaced apart so as to support the boxes near their opposite bottom corners, and, as may be seen in Figure 1, are trained about drive wheels 4 keyed to a drive shaft o whose ends are jo-urnaled in bearings 8. As appears at the opposite side of Figure l, the conveyor bands 2 are also trained about idler wheels 10 rotatably mounted on a xed shaft 12 whose ends are supported yby brackets i4 (Figure 3).

The lower run of the conveyor bands 2 is supported and guided by means of collars i6 (Figures 1 and 3) which *are rotatably supported on fixed shafts 17 extending across the lower portion of the machine near either ,end thereof and suitably supported.

The'upper run ofthe conveyor bands 2 is supported by a series of spaced rollers l and 2t) which in Figure 2 maybe seen to be of unequal length, and which rotate freely on stationary rods 22 the ends of which are secured to channel-shaped side rails 24 and 26. The rollers 13 and 20 are maintained in spaced relationship endwise by collars 2S secured tothe rods 22 by set screws. The space D between the inner ends of the rollers` i8 and 2t) serves a very useful purpose in accommodating boxes which are heavily packed with fruit or vegetables so that the bottom of the box is caused to bulge downwardly under the forces applied to the top or cover of the box when performing a closing operation. This space is also founduseful for handling crates carrying, for example, generally cylindrical cans or drums which project through the .openings between the slats at each side of the crate, as indicated by broken lines C in Figure 2.

The. drive shaft f5 and the drive wheels 4 keyed thereto aredriven in av clockwise direction, as viewed in Figure 1, by a gearl motor 3) which appears at the lower rightLin Figure l and whichhas a suitable driving connection with shaft 6. .The conveyor bands 2 are thereby continuously driven in the direction indicated by the arrow A.

Referring to Figures l and 3, and particularly to Figure 3, the reverse .L-shaped main framework of the closing machine includesbasemembers 32 and upstandingside members 34, suitably braced. The sidemmembers 34 are provided along .a major portion of their length with vertical slots 34a. (Figure 3) through which studs 36 vanchored in spacer blocks 3S (Figure l) project and are guidedverticaHy. .The spacer blocks 38 are secured to the .outer facel of the ,flanges of vertically extending channels40 at either side of an auxiliary framework vH, and serveto space the auxiliary framework from the inner 'faces ofthe main framework side members 34. Threaded on .the outwardly projecting ends of the aforementioned studs 3,6 areclampmembers 42 which may be tightened againstthe outer faces of the side members 34 to lock the auxiliaryV framework H in the desired vertical position -with'respect -to the main-framework.

When the .clamp members v42 are loosened, auxiliary framework H may be raised or lowered to accommodate 3 varying heights of box. The mechanism for accomplis lng this function is shown in Figures 5V and 6 and includes an adjusting shaft 44 whose ends extend vthrough openings in the upper portion of the main framework side members 34 a suicient amount to receive thereon a removable crank 46 (shown atthe right in Figure 5) for rotating said shaft. Rotatably supporting the adjusting shaft 44 are a pair of bearings 48 mounted on the inner si-de of the rear ange of side members 34. Keyed to adjusting shaft 44 adjacent the inner faces-of bearings 48 are sprockets 50 which have trained thereabout chains 52. One end of each of the chains 52 is anchored to the rear face of one of the channels of auxiliary framework H while its other end is attached to a counterweight 54` This counterweight 54 balances the weight of auxiliary framework H and reduces the effort which need be applied to crank 46 to move auxilitary framework H to the desired height.

As shown in Figures 1 and 3, the auxilitary framework H integrally supports on the front face of its channels 40 a pair yof overhanging arms 56 which have adjustably attached thereto a downwardly projecting presser bar 58 which maintains the top or cover of the box in closed position as the box moves into position. Also adjustably attached to said arms is a backing-bar 60 which engages the rear face of the box to cooperate with clamp bar 62 in securing the box in a fixed position during a closing operation.

Clamp bar 62 is supported and actuated by air-clamps or cylinders 64 mounted on a cross member 66 of auxiliary framework H.

As each box reaches proper box-closing position, air under pressure is supplied to the air clamps 64 to move the clamp bar 62 outwardly against the resistance of tension spring 68 (Figure 4) to a box-clamping position, indicated in Figure 4 by broken lines I, and after a suitable interval during which vthe box closure will have been completed, the supply of compressed air is removed and the tension springs 68 are allowed to return the clamp bar 62 to its withdrawn position, shown by full lines in Figure 4. The air supply to the air clamps 64 is controlled by a solenoid valve 70 which is controlled in turn by the sensing mechanism generally designated B and appearing in the central portion of Figure 1 and at the right in Figure 5.

The actuating member of this sensing `mechanism B lis a lever 72 having `one of its ends pivotally fastened at 74 to the outer face of side rail 26 and its opposite free end 72a bent at such an'angle that its uppersurface lies fiat against the under surface of the upper ange of side y The trip block 72b is urged upwardly by a coil spring i 76 interposed between the undersurface of the free end 72a of lever 72 and the uppersurface of the lower flange of side rail 26. To cooperate with lever 72 there is attached to the undersurface of the lower flangeof side rail 26 an electric start switch 78 whose actuating plunger 78a extends upwardly through an opening in said liange a suicient distance to engage the undersurface of lever 72. As each box nears the proper box closing position, it depresses the trip block 72b and lever 72 and trips the switch 78 and this, through an electrical circuit to be described hereinafter, results in actuating the solenoid valve 70 to supply compressed `air to the air clamps 64, causing them to move clamp bar 62 out to box clamping position and stop the box for the box closing operation.

The auxiliary framework H supports in its upper portion a transversely extending rocker shaft 80 whose ends are journaled in bearings 82 secured to the rear faces of channels 40 (Figures and 5). `Supported at one `end of the rocker shaft 80 (the right-hand end as viewed in Figure 1) adjacent .the inner faces of one of the channels 40 is a rocker arm 84 which as may be seen in Figure 3, projectscbothforwardly andrearwardly of the auxiliary framework. At the rearward end of the rocker arm 84 is fastened the upper end of a tension spring 86 the lower end of which is fastened tothe lower part of the auxiliary framework H. This spring 86 urges the rocker arm 84 and rocker shaft 80 in a counterclockwise direction, as viewed in Figure 3.

At the opposite end of the rocker shaft from the rocker arm 84 is another rocker arm 88 (see Figure 1) which projects only forwardly of the rocker shaft and irs of the same proportions as the similar projecting portion of rocker arm 84. Midway betweenthe arms 84 and 88, rockerr shaft 80 has fixed on it a main rocker lever 90 which projects rearwardly and is pivotally connected to the piston rod 92a of an air cylinder 92 (Figures 3 and 5v) which is secured to the lower portion of the auxiliary framework.

Pivotally fastened to the rocker armsv 84 and 88 adjacent their forward ends are a pair of `connecting links 94` (see particularly Figure 3) the lower ends of which are pivotally fastened to theforwardly extending arms 96a of crank members 96 (Figure 3). As shown particularly in Figure 7, the crank members 96 are joined at their lower ends by an angle cross brace 98 (see particularly Figure 7), whichrhas demountably secured to its frontface by lbolts 100 a closure bar 102 with a rounded bo-ttom face 102:1v As may be seen in Figure 1, the closure bar 102 extends the full width of the main framework and even beyond it at either side so as to engage all of the loop fasteners along the closing corner of the box.

Figures 3 and 7 show the position of the box closing elements in their initial position prior to a loop fastener bending operation. Asy may be seen in these figures the closure bar 102 is normally positioned to the outer side of the upwardly projecting loop fasteners F of the front side of the box, thereby eliminating any interference with these loop fasteners as the box is fed into position for the box closing operation.

To impart the closure bar 102 the complex movement lequired vfor properly bending the interengaged loop fasteners in securing the closing corner of the box, the supporting framework of the closure lbar 102 has rotatably mounted at its outer faces upper guide rollers 104 and lower guide rollers 106. The upper guide rollers 104 are received in guideways 108 formed by plates 110and A112 fastened to the front face of the channels 40 at either.

side of the auxiliary framework H, while the lower guide rollers 106 rest upon the upper surfaces of support plates 114 secured to the inner faces of plate members 116 which are mounted on the front faces. of channels 40 (Figure 7). At the rear of the support plates 114 are guideways 118 formed by the rear faces -of support plates 114 and the adjacent faces of cam plates fastened to the inner faces of channels 40.

Figures 8 through 10 show the successive positions through which these box closing elements pass during a box closing operation. This movement is imparted by rocking the rocker shaft 80 in a clockwise direction. In the rst stage, as shown in Figure 8, this causes the crank members 96 to pivot in a clockwise direction about the axis of the upper guide rollers 104, moving the lower guide rollers 106 rearwardly until they strike the forward surfaces of the cam plates 120. The rollers 106 will then be clear of the upper surfaces of the support plates 114 and in line with the upper ends of the guideways 118. During this rst phase of movement, the closure bar 102 will sweep arcuately over the closing corner of the box, .engaging the upstanding loops F and bending them outwardly in position to be bent back down along the front of the box.

Continued clockwise movement of the Arocker shaft 80, as shown in Figure 9, causes the crank members 96 to move translationally downward, with the upper and lower guide rollers 104 and 106 moving in their respective guideways 108 and 118. The resulting downward movement of the closure -bar 102 bends the loops E down against the front vside of the box and bends the loops F around the loops E.

As shown in Figure 10, the continued clockwise movement of the rocker arm 84 moves the crank members 96 translationally further downward to the point where the lower guide rollers 106 engage the forwardly curved lower portions 120a of the surfaces of the cam plates 120. These curved surfaces 120g force the lower guide rollers 106 forwardly, causing the crank members 96 as they move downwardly to pivot in a counterclockwise direction about the upper guide rollers 104. This causes the closure bar 102 to press the loops F downwardly and inwardly against the front sides of the box to complete the box closure. v

Clockwise movement of the rocker shaft 80 to move the closure bar 102 for the closure of a box in the manner describedis accomplished by supplying air under pressure to the air cylinder 92 (Figures 3 and 5), while this mechanism returned to its starting position prior to the next box closing operation by cutting olf the supply of compressed air to the air cylinder and allowing the spring 86 to move the rocker shaft 80 in a counterclockwise direction.

The supply of air to the cylinder 92 is controlled by means of a solenoid valve 122 (appearing at the left in Figure 3), which in turn is controlled by means of an electric switch 124, best shown at the center of Figure 4. This switch 124 is secured to the underside `of the lower cross member 66 of the auxiliary framework at a point lbetween the two air clamps 64. The actuating shaft of this'switch extends through an opening provided in cross member 66 and has adjustably mounted thereon a lever 126 bearing a roller 128 positioned to engage the rear face of clamp bar 62 in the withdrawn po-sition of the clamp bar. Outward movement of the clamp bar 62 toward its' box-clamping position (broken lines I), permits lever 126 to be urged by the mechanism of switch 124 to move in a clockwise direction, as viewed in Figure 4, from its initial position shown in full lines to the position indicated by broken lines K. This outward movement of lever 126 actuates the switch 124 so as to open the solenoid valve 122 and supply compressed air to cylinder 92, thus causing movement of the rocker shaft 80 and its assocated parts for a box closing operation.

The operation of the above-described mechanism is as follows:

Preparatory to feeding or placing boxes onto the conveyor ,bands 2, the top or :co-ver of the box is brought to -a closed position with each pair of loop fasteners E and F threaded one through the other, as indicated by broken lines G in Figure ll. The boxes are placed on the conveyor'bands 2 so that the boxes approaching trip block 72bon lever 72 are spaced apart a distance slightly greater than the dimension of the trip block as measured in a ldi- `rection parallel to the direction of movement of the boxes in order to permit lever 72 to move upwardly under the urging of coil spring 76 at least momentarily after each' box passes over it. Such a spacing of the boxes can be easily maintained by a single operator who also pushes down the top section of the box and interengages the loop fasteners E and F.

As the box is moved toward a position adjacent the loop fastener bending mechanism of the :closing machine, being partially guided by the outwardly ilared end of backing bar 60 and having its top or cover further closed and held by presser bar 58, trip block 72b is contacted and held depressed for the full length of the box, actuating the start switch 78.

As may be seen in the schematic diagram of Figure 14, this actuation of start switch 78 closes its normally open contacts 78h, andenergiz'es the solenoid o-f -a time-delay relay R which, as shown at the lower left in Figure 3, is housed in a box L attached to the main framework of the closing machine. The energization of the relay R 6 closes its normally open contacts R1 which are connected in `series with the normally closed but now open contacts 78C of start switch 78. As the trailing end of the box moves beyond trip block 72b (Figure l), lever72 is -moved upwardly to its initial position by coil spring 76, opening contacts '78!) of start switch 78 to rie-energize the solenoid of the time-delay relay R, and closing contacts 78C to apply current through the delayed opening relay contacts R1 to the solenoid valve '70. This actuates the valve 70 to'supply compressed air to air clamps 64 (Figure 4) and cause movement of the clamp bar 62 to clamp the box between it and the backing bar 60. The

box is thus held in proper position for the box closingoperation, with the conveyor bands 2 continuing to run but merely sliding ineffectually under the bottom face of the securely held box.

As the clamp bar 62 moves outwardly to box-clamping position, lever 126 of switch 124 is allowed to move outwardly as indicated in Figure 4 by broken lines K, closing switch 124 and, -as may be seen from Figure l4, energizing solenoid valve 122 and supplying compressed air to air cylinder 92 (Figure 3). This causes the piston rod 92a of the cylinder to move upwardly and move the rocker shaft 80 and the closure bar 102 to close the loop fasteners on the box. This box closing operation is completed within the ti-me-delay interval before opening of the contacts R1 of time-delay relay R.

With the completion of the time-delay interval, the contacts R1 of time-delay relay R open, breaking the circuit to solenoid air valves 70 and 122 which are de- `energized to `remove air 4pressure from cylinder 92 and air clamps 64. The relief of air press-ure in cylinderl 92 permits tension spring 86 to return the loop bending mechanism to its initial position, while the relief of pressure in air clamps 64 allows tension springs 63 to retract clamp bar 62, releasing the closed box, 4which is immediately moved from the path of the next oncoming box by the continuously moving conveyor bands 2.

A variation of the suspension of closure bar 102 is vShown in Figures l2 and 13, wherein said bar performs the function of closing the partially opened covers of the packed boxes in addition to bending the loop fasteners. As may be seen in said figures, the upper guide rollers 104 are dispensed with and the closure bar supporting assembly is pivotally supported on a pair of elongated arms 130 positioned at either side of the closure bar supporting framework adjacent the inner faces of crank members 132 which are connected to rocker arms S4 andSS by connecting links 94. One end of each of the elongated arms 130 is rotatably mounted on a cross shaft 134 the ends of which are journaled in bearings secured tothe inner faces of crank members 132 and maintained in position by stop collars 138. The opposite ends of elongated larms 130 are rotatably mounted on short shafts extending from brackets 142 secured to the upper surfaces of a flat cross member 144 fastened to the inner. faces of overhanging arms 56.

The construction of the framework supporting closure bar 102 is similarto that described hereinbefore. The lower guide rollers 106 are yreceived in'irregularly shaped guideways 146 formed in cam plates 148 and 149 attached to the inner face of brackets 152 mounted on the outer face of the channels 40 of auxiliary framework H and `cam plates attached to the inner face of channels 40.

As shown in full lines in Figure l2, the initial or raised position of closure bar 102 is of sufficient height to permit the partially opened cover of a packed box to pass beneath it as the box is fed into position to be closed. As has already been described, the sequence of operations by the mechanism of the closing machine is initiated by depression and release of trip block 72b as the box passes over it. In this latter embodiment of the machine, the path of movement of the closure bar 102 is such that it 'first contacts the partially opened box cover and, Ias it moves downwand arcuately to the position shown in YAt Vthis point in the movement of closure bar 102, the

lower guide rollers 106 contact and move rearwardly on a horizontal step 148a of -cam plate 148, causing closure bar 102 to move over the edge of the box cover while pressing it tightly closed and then move downwardly to bend the threaded loop fasteners 'F and E in the manner previously described.

From the foregoing description, it will be apparent that the present invention provides a practical machine for automatically closing wirebound boxes. It will therefore be appreciated that the above mentioned desirable objectivesvhave been achieved. However, it should be emphasized that the particular embodiments of the invention shown and described herein are intended as merely illustrative and not as restrictive of the invention.

I claim:

l. A machine for closing wirebound boxes of the type having interengageable loop fasteners at their closing corners comprising a pair of clamp members for engaging opposite faces of said boxes and holding said boxes stationary in a predetermined position, a movable loop bending member adjacent to and aligned with the positions of a pair of interengageable loops at the closing corner of a box in said predetermined position, a cam member lcooperating with said loop bending member for guidthe front of the box, and motor means for driving said loop bending member along said path.

2. A machine for closing wirebound boxes of the type -having interengageable loop fasteners atY their closing corners comprising a conveyor for moving said boxes `into and out of said machine, a pair ofclamp members for engaging opposite faces of said boxes, at least one of said clamp members being movable from and into engagement with the adjacent face of said boxes to grip said boxes between said clamp members and hold them stationary in a predetermined position, a movable loop bending member adjacent to and aligned with the positions of a pair of the interengageable loops at the closing corner of a box in said predetermined position, a cam member cooperating with said loop bending member for guiding the same in a path extending first obliquely downward against and across the top of the box past its closing corner, vthen downwardly along and generally parallel to the front of the box and finally inwardly toward the front of the box, motor means for moving said movable clamp into engagement with said boxes and for moving said loop bending member along said path, a sensing element connected to control said motor means and arranged to be actuated by said boxes as they move toward said predetermined position, whereby said boxes will be stopped and held in said predetermined position by said clamp members and the loops on said boxes will be bent into box-closing position by said loop bending member.

3. A machine for closing wirebound boxes of the type corners comprising a conveyor for moving said boxes into and out of said machine, a first motor means for continuously driving said conveyor, a pair of clamp members for engaging opposite faces of said boxes, at least one .60 having interengageable loop fasteners at their closing of said clamp members being movable from and into engagement with the adjacent face of said boxes to grip said boxes between said clamp members and hold them stationary in predetermined position, a second motor means for moving said movable clamp member into engagement with said boxes, a first sensing element .Connected to control said second motor means and arranged to be actuated by said boxes as they move toward said predetermined position, whereby said sensing element will cause movement of said movable clamp member into l engagement with said boxes to hold said boxes in said predetermined position, a movable loop bending 'member adjacent to and aligned with the positions of a pair of linterengageable loops at the closing corner of a box in said predetermined position, a cam member cooperating with said loopbending member forlguiding the same in a path extendingirst obliquely downward against and across thetop of the box past its closing corner, then downwardly along and generally parallel to the front of the box and finally inwardly toward the front of the box, a third motor means for driving said loop bending member along saidV path, a second sensing element connected to control said second motor means and arranged to be actuated in accordance with the position of said movable clamp member whereby movement of said movable clamp member into engagement with saidbox will initiate movement of said loop bendingy member to bend said loops. l v

4. In a machine for closing wirebound boxes of the type having interengageable loop fastenersY at their closing corners, mechanism for bending the loop fastenersy of boxes held stationary within said machine comprising a supporting shaft mounted for translational movement ina direction generally parallel to the front of the box, a crank assembly pivotally supported on said shaft for arcuate movement aboutan axis generally parallel to the closing corner of the box, said crank assembly having l a rst crank arm extending toward said box and a second crank arm extending in a direction generally rearward with relation to said box, a loop engaging portion at the end of the said first crank arm adjacent said box, drive means connected to the rear end of said second arm to urge said crank assembly to move translationally downward and to pivot in an arc swinging saidV loop engaging portion obliquely downwardly and forwardly relative to said box, and a cam having a cam surface generally parallel to the front of said box for engaging a portion of said crank assembly and limi-ting its movement in a direction forwardly with relation to said box, whereby such actuation of said drive means causes said loop engaging portion to move arcuately downwardly and forwardly across the closing corner of said box. until said crank assembly strikes said cam surface, and then downwardly along the front of said box.

5. In a machine for closing wirebound boxes of the type having interengageable loop fasteners at theirclosing corners, mechanism for bending the loop fasteners of boxes held stationary within said machine comprising a supporting shaft mounted for translational movement in a direction generally parallel to the front of the box, a crank assembly pivotally supported on said shaft for arcuate movement about an axis generally parallel to the closing corner of the box, said crank assembly having a first ycrank arm extending toward said box and a second crank arm extending in a direction generally rearward with relation to said box, a loop engaging portion Vat the end of the said iirst crank arm adjacent said box, and a cam having a cam surface adapted to engage a portion ofl said crank assembly and limit its movement forwardly with relation to said box, the upper portion of said cam surface extending generally parallel to the front of said box and the lower portion of said cam surface being inclined inwardly toward the front of said box, whereby such actuation of said drive means causes said loop engaging portion to move varcua'tely downwardly and forwardly across the closing corner of said box until said crank assembly engages said cam, then to move downwardly along the front of said box and finally inwardly toward the front of said box.

References Cited in the file of this patent UNITED STATES PATENTS 

